Study assesses protective capabilities of DNA vaccines against SIV

Inovio Biomedical Corporation (NYSE Amex:INO), a leader in DNA vaccine design, development and delivery, announced today that data generated from a pre-clinical collaborative study by National Cancer Institute (NCI) and Inovio scientists were published in the scientific journal Proceedings of the National Academy of Sciences in a paper entitled: “DNA vaccination in rhesus macaques induces potent immune responses and decreases acute and chronic viremia after SIVmac251 challenge.” The senior author of this study is Dr. George Pavlakis, Senior Investigator & Chief, Human Retrovirus Section Vaccine Branch, NCI.

The primary aim of this study was to assess protective capabilities of optimized DNA vaccines delivered using Inovio’s proprietary electroporation system against simian immunodeficiency virus (SIV), which is closely related to human immunodeficiency virus (HIV). Animals receiving an NCI vaccine were challenged 14 weeks after a four-dose vaccination regime with a highly pathogenic strain of SIV and followed for 32 weeks post-challenge. Vaccinated animals exhibited greatly reduced viremia (the spread of a virus via the bloodstream) during acute and chronic phases of infection compared to control animals, indicative of better control of infection.

Vaccinated animals developed strong cellular and humoral responses against the DNA vaccine antigens. Vaccination induced strong memory responses that were maintained at the day of challenge. Development of high levels of effector memory T cells suggested the potential for rapid immune system mobilization upon SIV challenge. These results demonstrate that DNA vaccines delivered using only electroporation, without a heterologous boost with, for example, an alternative vaccine modality such as a viral vector-based vaccine, can provide acute and chronic protection from high viremia that is comparable to other vaccine modalities that have been previously tested in this macaque model.

At a recent scientific conference, Dr. George Pavlakis, Senior Investigator & Chief, Human Retrovirus Section Vaccine Branch, NCI, stated that on the challenging path toward an HIV preventive vaccine, various alternative vaccine modalities have faced challenges including being unable to induce sufficiently strong immune responses, or inducing unwanted immune responses. In this study, an electroporation-delivered plasmid-based DNA vaccine achieved some of the highest levels of humoral and cellular immune responses against SIV ever achieved by a DNA vaccine, without the aforementioned issues. Dr. Pavlakis stated that he believes electroporation is presently the gold standard for DNA vaccine delivery, generating the best results in terms of immunogenicity of DNA vaccines and producing both antibodies and cytotoxic T cells in response to the DNA vaccination. The immune responses and level of protection achieved in this experiment are among the highest reported by any vaccine approach in this macaque model. Furthermore, Dr. Pavlakis indicated that the positive results of this study suggest that further research of this approach should be a high priority.

Dr. J. Joseph Kim, Inovio’s CEO, said, “We are pleased to have achieved these important results with a prestigious research organization such as the NCI. This new knowledge will help advance Inovio’s DNA vaccine technology platform and our broad preclinical and clinical pipeline encompassing human papillomavirus, influenza, and other infectious diseases. We look forward to initiating a human trial with our proprietary electroporation-delivered HIV DNA vaccine this fall.”

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